Fuel cells are used or have been proposed as a power source in many applications, such as in electrical vehicular power plants to replace internal combustion engines and in stationary applications to produce electrical power. In proton exchange membrane (PEM) type fuel cells, hydrogen is supplied to the anode of the fuel cell and oxygen is supplied to the cathode. PEM fuel cells include a membrane electrode assembly (MEA) comprising a thin, proton transmissive, non-electrically conductive solid polymer electrolyte membrane having the anode catalyst on one of its faces and the cathode catalyst on the opposite face. The MEA is sandwiched between a pair of electrically conductive elements which serve as current collectors for the anode and cathode, and contain appropriate channels and/or openings therein for distributing the fuel cells' gaseous reactants over the surfaces of the respective anode and cathode catalysts. A typical PEM fuel cell and its MEA are described in U.S. Pat. Nos. 5,272,017 and 5,316,871 issued respectively Dec. 21, 1993 and May 31, 1994 and assigned to General Motors Corporation.
The term “fuel cell” is typically used to refer to either a single cell or a plurality of cells depending on the context. A plurality of individual cells are commonly bundled together to form a fuel cell stack. Each cell within the fuel cell stack comprises the MEA described earlier, and each MEA provides its increment of voltage.
Precise alignment of the components of a fuel cell stack to a predetermined orientation is desirable. The components of a fuel cell stack have typically been aligned during assembly by using external elements to surround or cage the components according to their corresponding perimeters. However, such external elements may limit access to various components during assembly. Additionally, higher tolerance levels are desired than can be provided by such external components. Accordingly, it would be desirable to align the components of a fuel cell stack using internal features.